A variety of techniques are used to detect the presence of acids, acidic substances, bases and basic substances in liquids. For example, electronic devices such as pH meters can be used or chemical detection techniques such as Litmus paper can be used.
The detection of the presence of acids or bases in gases is more difficult and is becoming increasingly important. In a variety of work and other environments, acidic or basic gases may be present, and their presence can provide a hazard to those exposed to these gases. Techniques suitable for the detection of acids or bases in liquids typically are not suitable for the detection of acids or bases in gaseous media.